I suspect geums are often considered dull because they're easy to grow, being hardy and largely self-reliant.

And if you're fed up fattening your slugs on salvias, why not try unpalatable geums instead?

Yet geums brighten any border, contrasting and complementing so many plantings. Take the fiery orange blooms of Geum "Prinses Juliana" jostling among the juicy greens of euphorbias and you'll see what I mean.

If you don't know or would like to buy "Prinses Juliana", look out for it at the MacPlants stand at Gardening Scotland, the country's foremost horticultural show, next weekend. Gavin McNaughton of MacPlants tells me he will have lots of geums, including a favourite at the annual show, "Flames of Passion", with up-facing soft red flowers from dark stems, as well as "Lemon Drops" and "Totally Tangerine".

"Totally Tangerine" is one of the many new varieties that are constantly added to an already lengthy list of cultivars. This geum produces a profusion of apricot blooms throughout the summer; towering above clumps of divided, toothed and scalloped foliage, they provide an impressive display.

Some recent additions from the USA include G "Alabama Slammer", which has a burgundy purple calyx opening to gold with red orange markings. "Tequila Sunrise", meanwhile, has soft red-flushed yellow to apricot flowers.

Geums can be divided into four main groups: Geum rivale, G chileonse, G coccinium and G montanum. Geum rivale, water avens, is the wild native species and grows everywhere in Scotland apart from the Western Isles. You'll find it in sun or partial shade in calcareous or mildly acidic soil. Like all its brethren, G rivale needs moist conditions and tolerates marshy ground. You can even find G rivale "Album", an outstanding native perennial, growing in shallow water. Its clumps of rounded, lobed leaves with tall grey-green stems bear charming nodding bell-shaped pale green-white flowers. They're followed by small burr-like seedheads.

As a fan of almost any lemon-coloured flower, G rivale "Lemon Drops" appeals to me, its single, soft yellow flowers drooping delightfully over rich, green basal leaves.

The Geum coccineums are small to medium-sized clump-forming perennials. One classic is G "Borisii", with a mass of single tangerine-orange flowers, growing to 30cm. G "Mango Lassi" is a frilly double, its pale apricot flowers with gold undertones edged with coral-rose.

Geum chiloense cultivars, from the Chilean island of Chiloe, are slightly larger than coccineums. They have strong stems and large, mainly double flowers. The deep scarlet flowers of "Mrs J Bradshaw" are 5cm wide. The semi-doubles blend well with the strikingly attractive golden yellow "Lady Stratheden". This superb geum, like its fellows, keeps on flowering right through the summer.

Tall, graceful geums like these work well in the middle or towards the back of a border, but G montanum, the alpine or mountain avens, is the perfect edging plant. This tiny, dense clump-former produces a blaze of charming cup-shaped yellow flowers.

So there's a geum for every part of the border and you're assured a long flowering period, but you will need to rejuvenate a clump periodically, possibly as often as every two or three years. Lift and divide when a clump becomes like a doughnut, with a bare centre, surrounded by growth. Do this in spring or autumn, replanting the fresh outer plants immediately and discarding the centre.

There's one downside to geums. They hybridise all too promiscuously and will colonise a bed with admirable alacrity. This may not matter in some places, but you can prevent it by deadheading. As usual, you'll prolong the flowering season, even if you miss the charming puffball seedheads in autumn.